This study revealed the effects of different olive sizes on some physical properties, oil content, bioactive components, fatty acid, α‑tocopherol and phenolic component profiles of “Gemlik” olive fruits from Mersin (Mut) province, Turkey. Physical measurement results of olive fruits differed according to olive sizes. The width and height of olive fruits were recorded to be between 15.91 mm (small) and 18.26 mm (large) to 20.10 mm (small) and 24.35 mm (large), respectively. The oil amounts of olive fruits at different sizes were recognized to be between 52.31% (small) and 60.14% (large). Total phenolic and flavonoid amounts of olive fruits at three different sizes were reported to be between 328.86 (medium) and 423.49 mg GAE/100 g (large) to 1348.25 (medium) and 1745.08 mg/100 g (small), respectively. Antioxidant capacity values of olive fruits at different sizes were recognized to be between 9.78 (small) and 9.82 mmol/kg (large). Verbascoside, luteolin-7-glucoside, rutin trihydrate, apigenin -7-glucoside and oleuropein were the highest phenolic components found in olive fruits of different sizes. Oleic acid was found at the highest levels in oils obtained from olives of all three sizes, followed by palmitic, linoleic and stearic acids in decreasing order. The α‑tocopherol contents of the oils extracted from olives at different sizes were defined to be between 24.25 mg/100 g (medium) and 30.55 mg/100 g (small). It can be seen that the highest α‑tocopherol was detected in the oil obtained from small olives, followed by large and medium olives in decreasing order.